Summary of Revision, IEEE C , Guide for Breaker Failure Protection of Power Circuit Breakers

Transcription

1 Summary of Revision, IEEE C , Guide for Breaker Failure Protection of Power Circuit Breakers Kevin Donahoe GE Grid Solutions 2018 Texas A&M Protective Relaying Conference

2 Agenda Introduction Breaker Failure Minimal Current Scheme Current Differential Breaker Failure Protection Column Ground Protection Breaker Failure Protection for Generator Applications Redundant Control Circuits Conclusions Questions

3 Introduction Replaced C PSRC Working Group followed up with the paper Summary of Revision, IEEE C , Guide for Breaker Failure Protection of Power Circuit Breakers Definition of breaker failure protection (BFP) 2005: This protection is specifically relied upon to take appropriate action to clear a fault when the breaker that is normally expected to clear the fault fails to do so for any reason. 2016: A form of protection that is designed to detect the failure of a circuit breaker to operate or to interrupt a fault. Upon detection of a breaker failure during a fault condition the scheme is designed to take appropriate action to clear the fault. Upon detection of a breaker failure during a nonfault condition, the scheme may take other appropriate action.

4 Introduction Covered in C37.102, IEEE Guide for AC Generator Protection BFP can fall in overlap between generation and transmission Added clause increase familiarity with the unique requirements for generator BFP IEEE-Standards Association asked to expand the scope of the C Now includes performance failures of breakers other than fault clearing failures Failure to close during synchronizing is now covered

5 BF Minimal Current Scheme Breaker failure applications associated with highimpedance power system apparatus, such as generators, transformers, static var compensators (SVC), and harmonic filters, may have such low currents associated with internal faults that current detectors are not reliable. BF logic can also be achieved using breaker auxiliary switches

6 BF Minimal Current Scheme Considerations

7 BF Minimal Current Scheme

8 BF Minimal Current Scheme

9 BF Minimal Current Scheme False BFI one cause, accidental battery ground Measures to reduce possibility of false BFI BFI input that responds only above half of the maximum battery voltage Binary inputs are compliant with IEC , Measuring relays and protection equipment Electromagnetic compatibility requirements with specific reference to Clause 7.2.7, Power frequency immunity on DC binary inputs Minimize cable run length and capacitance Data communication-based means for conveying the BFI between buildings

10 Current Differential BFP Accurate fault diagnosis Extra installation and maintenance cost Logical condition of adjacent operation of protection zones

11 Column Ground Protection CT column changes BFP No overlap Most likely: column to ground flashover CTs around the base of each column Direct trip of 86 IEEE Std. C37.234: Buses

12 BFP for Generator Applications Mechanical Indication of Breaker Status CT Locations Open Generator Breaker Flashover Protection Breaker Arrangement: High-Side Breakers Breaker Arrangement: Low-Side Breaker Generator Breaker Failure to Close Protection

13 Mechanical Indication of Breaker Status Consider, in a motoring event, failure to separate from the power system can damage the prime mover A steam turbine has a typical motoring power range.5-3% CTs sized for 5A at generator rating current in milliamps CTs on dual breakers, CTR may be based on bus rating Current measurement is not reliable for all conditions requiring BFP

14 CT Locations Even after the breakers open, the generator will feed a inzone fault until stored energy in the field dissapates Never use generator neutral CTs For low-side breaker location, not appropriate to use generator terminals CTs that measure the current flowing directly into the breaker

15 Open Generator Breaker Flashover Protection Flashover most likely to occur just prior to synchronizing or just after the generator separates

16 Open Generator Breaker Flashover Protection

17 Breaker Arrangement: High-Side Breakers

18 Breaker Arrangement: High-Side Breakers

19 Breaker Arrangement: High-Side Breakers

20 Breaker Arrangement: Low-Side Breaker For Faults Trip the generator CB G Open the generator field breaker Isolate the energy source that drives the prime mover

21 Generator BF to Close Protection Synchronizing systems minimize: Speed difference or slip rate Voltage difference Angle difference Main contacts make at the instant when the angle difference is as near to zero as possible If breaker mechanism is slow then the generator rotor angle will pass zero and start increasing BFP could isolate the synchronizing breaker so that the generator closes into a dead bus

22 Generator BF to Close Protection

23 BFP on Redundant Control Circuits

24 Conclusions Summary of Revision, IEEE C , Guide for Breaker Failure Protection of Power Circuit Breakers is available at psrc.org/kb/published/reports/paper_summaryofrevc pdf Go to pes-psrc.org Go to Knowledge Base Go to Reports D subcommittee or search for 119

25 Thank You Questions?